The overall objective of this research project is to gain knowledge of the initiation and control of wound healing in ocular tissue. Discovery of the "trigger" mechanisms which initiates wound healing and the further mechanisms which regulate and control the repair process is the long-term focus of this research project. We have obtained a mesodermal growth factor (MGF) which greatly accelerates the normal wound healing process of rabbit and corneal stroma in vivo and of human endothelium in organ culture. These responses result from a single short-term exposure to MGF. We have purified two components, MGF-I and MGF-II, from the MGF preparation and have demonstrated that they act synergistically as potent stimulants of stromal cells in tissue and organ culture. The proposed studies address the following topics: a) mesodermal growth factor synergism and interaction with corneal endothelial and stromal cells; b) corneal endothelial wound repair; and c) influence of aging of healing responses of corneal endothelial and stromal cells. Standardized freeze-thaw injuries of whole corneas will be used to study corneal endothelial wound repair in organ culture and in tissue culture. The details of each experimental procedure will be first established on rabbit corneas which are readily available. The optimal procedures obtained will be applied to human, dog, and monkey corneas. Tissue culture cells of both the corneal stroma and endothelium will be used to explore specific mechanisms which are not amenable to attack in organ culture. Light and scanning electron microscopy will be used to evaluate changes in cell morphology, cell adhesion, and cell growth rates in response to growth factor stimulation of corneal stromal and endothelial cells. Alterations in cell surface proteins and in the cell cycle will be analyzed biochemically. Binding and/or internalization of growth factor(s) will be analyzed by immunofluorescent and immunoferritin techniques. Comparisons will be made between young and aged cells as well as between normal and freeze-injured corneal endothelial cells. Understanding the events described is of importance not only to basic biology but also to those fields of clinical medicine concerned with cell growth and wound repair.